Timing and duration of mare basalt magmatism: constraints from lunar samples

One of the important issues in lunar science relates to the understanding of the timing and duration of mare magmatism which has significant implications for the thermal evolution of the lunar interior through time. Remote sensing studies of the Moon have indicated existence of mare regions as old as 4 Ga and as young as 1 Ga. In contrast, most lab-based studies involving direct age dating of “returned” basaltic lunar samples (from Apollo and Luna missions, and lunar meteorites) by radiometric techniques have yielded much narrower age ranges for mare magmatism, typically in the time interval of 3.9 to 3.1 Ga. However, less attention have been given to some notable examples of ancient mare magmatism, samples of which exist in terms of 4.2 – 4.3 Ga basalts. Recently, a number of chronological investigations of basaltic lunar samples have revealed crystallization ages which are older, as well as, younger, than previously known range for mare basalt ages. These new findings have necessitated revisiting the topic of ages and duration of basalt volcanism on the Moon and the causes and consequences of it for the lunar evolution with implications for post-accretion planetary differentiation processes